Gabriel Douglas has built his reputation on the churning, heavy-thumping blues rock of the 4onthefloor, whose sound is defined as much by his wild man warrior-bellow vocals as it is by the steady pulse of the four members’ synchronous bass-drum thuds—but a delve into the corners of his catalog reveals an artist with a startling breadth of interests. The man keeps busy, holding down gigs in several stylistically distinct groups while regularly performing and recording solo. The solo shows let the guttural howls show through and the songs breathe new lives as stripped-down road songs.